1. Field of the Invention
The present invention relates to supplying power to a computer system, and more specifically relates to supplying power to a computer system when a power supply fails.
2. Background of the Related Art
A computer system is typically powered by one or more electrical power supplies intended to provide a continuous supply of power. An electronic power supply converts electricity from an electrical power source, such as an alternating current power outlet, to a form usable by a computer system and its various components. For example, a power supply may step-down voltages from a higher-voltage power outlet and convert alternating current (AC) to direct current (DC), to supply electrical power at one or more desired amperage and voltage.
Computer systems generally require a reliable source of electrical power to function properly. In the event of a power supply failure, calculations and data that required valuable processing time may be lost. A power supply failure can also lead to damaged computer components by suddenly removing power without the system having been properly shut down.
Redundant power supplies may be provided in a computer system in order to increase reliability of operation. Conventional systems providing power redundancy involve the use of additional power supplies, so that if one power supply fails, another power supply is available to compensate for the failed power supply. A simple system may, for example, provide “N+N” redundancy where a number (N) of computer systems are each provided with a number (N) of primary power supplies and a number (N) of secondary power supplies. In such a system, there are twice as many power supplies as computer systems. A further system may provide “N+1” redundancy, such that a number (N) of computer systems are grouped together and provided with a number (N) of power supplies (i.e., one power supply per computer system), plus a single (+1) backup power supply that can provide the power needed if any one of the N power supplies fails.
Power supplies take up valuable space and add significant capital costs, however, particularly in larger computer systems, such as rack-mountable server systems, that already require multiple power supplies. As a consequence, the increased reliability afforded by conventional systems providing power redundancy generally results in larger and more expensive systems.